Filament spool



FIG. 1 is a top perspective view of a design for a filament spool.

FIG. 2 is a bottom perspective view of the design.

FIG. 3 is a top view of the design.

FIG. 4 is a bottom view of the design.

FIG. 5 is a left side view of the design.

FIG. 6 is a right side view of the design.

FIG. 7 is a front view of the design; and,

FIG. 8 is a back view of the design. 

CLAIM What is claimed is the ornamental design for a filament spool, as shown. 